Are speedometer sensors Hall Effect types ?

[potoole64]

My 97 Harley Sportster has a speedometer sensor and a cam position sensor. Are these type of sensors Hall Effect types?
If the speed sensor is, can another test ckt. be connected to that sensor, and still have the speedometer operable?

The Harley repair manual gives directions on making a test harness which would connect (T-off) to the speed sensor? Would connecting other circuitry in this manner cause damage to the sensor?
Would the same be so with the cam position sensor?

Thanks
Patrick

 

[picbits]

Most sensors I've come across in designing stuff for cars has been hall effect or similar. Some use cable driven speedos but have an IR sensor which captures a spinning disc inside the speedo.

In response to your question, you can normally add on other stuff to the speed sensor. As for damaging it, it depends on what it is you're connecting. If you're really worried, use a 2.2k resistor in series with the speed pulse and either use it directly if your device will support it or buffer it with a transistor.

Even a dead short to +ve or GND will only be around 6.2mA if you feed it through the resistor.

 

[buddrow]

Is the sensor 2-wire or 3-wire? if its 3-wire it should be a digital sensor, if it's a 2-wire it may be a PM generator and thus will be an ac voltage.

 

[potoole64]

buddrow asked:

Is the sensor 2-wire or 3-wire? if its 3-wire it should be a digital sensor, if it's a 2-wire it may be a PM generator and thus will be an ac voltage.

Its three wire

thanks
Pat

 

[buddrow]

Then it should be a digital output at I stated before. There will be a ground, a reference, and a signal wire. The reference will likely be 5volts and you will want to tap into the signal wire which you should find easily by checking each wire for ground, voltage and one "dead", provided the vehicle is stationary, wire which will be the signal. Hope this helps.

Bud

 

[picbits]

On a lot of the ones I've used there has been a +12v, GND and signal wire.

The signal wire is a pulldown output i.e. it pulls the signal wire to ground when it detects a pulse.

The dashboard or trip computer usually provides the pullup current to complete the circuit.

 

[power58]

If you can borrow or build a breakout box for the Harley ECM you could monitor the signals from the cam sensor and speedo sensor. A breakout box is great for design work.
the factory ones are very expendsive $400 or more. Building one would not be to bad if you can find the right connectors.

 

[potoole64]

If you can borrow or build a breakout box for the Harley ECM you could monitor the signals from the cam sensor and speedo sensor. A breakout box is great for design work.
the factory ones are very expendsive $400 or more. Building one would not be to bad if you can find the right connectors.

What is a "breakout"? I've seen that term used before: breakout circuits, breakout cards, etc.

Thanks to all for the help
Pat

 

[power58]

The Term breakout box comes from your ablity to "break out" a particular wire and monitor it with out damaging the wiring harness. You unplug the male connector from your Harley computer and plug it into the female connector on the break out box. A male connector on the breakout box plugs into the Harley computer. The break out box will have pin jacks that you can put a scope or voltmeter on. Each wire on the box has a pin jack. The box wiring is stright through. Pin 1 on the female connector goes to jack 1 then to pin 1 on the male connector . It is easy to wire a breakout box but labor intensive is you have 40 pin or more connectors.